I take my very hot mare over a line of 3 small cross rails at 2 stride distance 2 days before the show and I don't ride her the day before. This grid allows me to work her over small jumps. I take them while in circles, but circles in between them. Take them 1,2 or 3 at a time. All the combinations to get her working with me and thinking.
But in the end it depends on the horse. My last horse I would jump him over a course at the barn the day before and he would be all set.